2-in-1 Digital RPM Tachometer | Non-Contact Photo Sensor Tachometer 3~99,999RPM and Contact RPM Gauge Tester 3~19,999RPM Tach Speed RPM Meter with 4 Contact Probes, Data Hold, Max/Min, Backlit LCD

worked great

Setting high idle on motor working great

Used it on my tractor to find the rpm range to get the 540 from my PTO

When I ordered this, I didn't understand how the touch mode worked. For some reason, I thought it was basically a vibration sensor, but that's not true. It has a spinning axle that you can attach to the rotation you're trying to measure. It comes with a pulley that can be driven by a cord or just used as a wheel, a 15mm diameter cone, a 9mm diameter cone, and a 10mm cup. These are all made of relatively pliable rubber that shouldn't slip on things you touch them to. (The core of the pulley is solid plastic.) This mode can also measure distance in tenths of meters, based on the circumference of the pulley. (Also m/s and ft/s, also based on the pulley.)There's also the non-touch sensor that emits a beam of light that has to be reflected back. It comes with about 3 feet worth of reflective sticker. I have found that it has problems if the thing you're measuring is already reflective, like metal fan blades, but seems to work well otherwise.It has a backlight and is powered by two AAA batteries, included.The body is well constructed and the red sides are a slightly grippy rubber.

This is a cool bit of kit. The mechanical and optical sensor seem to line up pretty closely, and swapping between different testing heads and modes is a breeze. Highly recommended.